1. Field of the Invention
The present invention relates to a facsimile gateway device for inverting a packet data into a facsimile image data, which serves as a second gateway device in a real time Internet facsimile communication system adapted to transmit the facsimile image data from a data transmitting communication terminal device such as a facsimile machine to a data receiving communication terminal device such as a remote facsimile machine via a first communication network (e.g., a public switched telephone network), a first gateway device for converting the image data into the packet data, a second communication network (e.g., the Internet), the second gateway device, and a third communication network (e.g., the public switched telephone network).
2. Description of the Related Art
A real time Internet facsimile communication system for transmitting an image data from one facsimile machine to another facsimile machine via a public switched telephone network, a first gateway device for converting the image data into a packet data, the Internet, a second gateway device for reconverting the packet data into the image data, and the pubic switched telephone network, under a communication procedure same as the facsimile communication procedure in accordance with ITU-T (International Telecommunication Union) Recommendation T. 30 is realized (hereafter referred to as the “conventional example”). Such conventional example is defined in ITU-T Recommendation T. 38.
According to such conventional example, a general facsimile machine on the transmitting side transmits a facsimile image data under the facsimile communication procedure in accordance with ITU-T Recommendation T. 30 to the first gateway device via the public switched telephone network. The first gateway device converts the image data into a predetermined packet data and transmits the packet data to the second gateway device via the Internet. Then, the second gateway device reconverts the packet data into the facsimile image data and transmits the image data to a destination facsimile machine via the public switched telephone network. The communication procedure signal used between the facsimile machine on the transmitting side and the facsimile machine on the receiving side is similar to a facsimile communication procedure signal defined in ITU-T Recommendation T. 30. The facsimile data communication between the two gateway devices is carried out using the packet data.
The above described conventional example has an advantage in that a communication expense for transmitting the facsimile image data can be suppressed since the overall distance in the public switched telephone network is shortened.
As mentioned earlier, the second gateway device is expected to receive the image data via the Internet and transmit the image data to the remote facsimile machine in real time via the public switched telephone network. However, there is a certain delay in the transmission via the Internet, and therefore the second gateway device sometimes cannot transmit the image data to the remote facsimile machine via the public switched telephone network in time.
In order to overcome such problem, a flow control is applied to the second gateway device when transmitting and receiving the image data. However, a manufacturing cost is increased due to a complicated program for the flow control.